Internally expanding brake



Jan. 3, 1950 E. ZIPPER 2,493,055

INTERNALLY EXPANDING BRAKE Original Filed May 20, 1940 5 Sheets-Sheet 1 (.9 V v IIIIIIIII 4 V mmssaff I r V if IVENTOR.

MIL Z/PPER j Jan. 3, 1950 Z|PPER 7 2,493,055

INTERNALLY EXPANDING BRAKE Original Filed May 20, 1940 5' Sheets-Sheet 2 INVENTOR. E MIL Z/PPEE 5 Sheets-Sheet 3 Original Filed May 20, 1940 INVENTOR. E MIL Z/PPE/a Jan. 3, 1950 E; ZIPPER $493,055

1 IN'EERNALLY EXPANDING BRAKE Original Filed May 20, 1940 5 Sheets-Sheet 4 106 jag 1% 1M wg /i w v gg Jan. 3, 1950 E. ZIPPER 2,493,055

INTERNALLY EXPANDING BRAKE Original Filed May 20, 1940 5 Shets-Sheet 5 lNVEN TOR. E MIL Z/PPEE Patented Jan. 3, 1950 2,49ao55 INTERNALLY EXPANDING BRAKE Emil Zipper, Santa Monica, Calif.; vested in the Attorney General of the United States Original application May 20, 1940, Serial No. 336,299. Divided and this application May 29, 1945, Serial No. 597,341. InGreat Britain May This invention relates to brakes and more particularly although not essentially to brakes suitable for road vehicles such as omnibuses and to aeroplanes. The present application is a division of my copending application Serial No. 336,290, filed May 20, 1940, now Patent No. 2,376,889, which issued May 29, 1945.

The main objects of the invention are to provide means of simple constructional form for operating brake shoes which will provide efficient servo action and parallel brake motion.

In order that the invention may be more clearly understood, it will now be briefly described with reference to the accompanying drawings, in which:

Figure 1 is a side elevational view of a brake made in accordance with the invention.

Figure 2 is a sectional view onthe line 2-2 in Figure 1.

Figure 3 is a section on the line 3-3 in Figure 1.

Figures 4, 5, 6 and 7 are side elevations showing modified constructions of brakes made in accordance with the invention. 1

Figures 8, 9, 10 and 11 are sectional views on the lines 88, 9-9, H! and in Figure 7, and

Figure 12 is a side elevational view of a modified form of brake made in accordance with the invention.

In Figures 1, 2 and 3:

The brake carrier l which is fixed to the axle casing has an annular flange 2 on which two axially spaced guiding rings 3 and 4 are rotatably mounted. Each of these two guiding ringshas two lugs 5, 6 and 8 which are 180apart. Corresponding pivot pins |3, I4 and |5,'|6 are arranged rotatably in holes in these lugs. Corresponding levers 9, l9 and II, l2 are connected at one end to these pivot pins. In each of the brake shoes 2| 22 are twoholes located adjacent to their ends, in which corresponding pivot pins l1, l8 and I9, 29 have their bearing. The remaining ends of the levers 9, |9, l2, are connected to the last mentioned pivot pins. Slots 25 and 26, are provided in the middle of the brake shoes 2| and 22, respectively, through which pass pins 23 and 24, respectively, that are fixed in the brake carrier Levers 21. and 28, on the pins 23 and 24 have their opposite ends pivoted on the pins 23 and 24 and the bolts l9, and I1, respectively.

On each of the pins l3 and I is pivoted a corresponding guiding piece BI, 32, which can slide 6 Claims.

tangentially in corresponding cam blocks 35, 36.

The sliding movement serves for the adjustment of the brake shoes and is carried out by worms 33, 34 and worm wheels 29, 39. The worm wheels 29, 39 are fixed to bolts 31, 38, having their nuts in the connecting blocks 3|, 32. The cam blocks 35, 36 are mounted on the rings 3 and 4 in a manner to permit some circumferential movement but prevent any radial movement of the blocks relative to the rings. By turning the cam 39 out of the position shown in Figure 1 the blocks 35, 36 are moved apart. The distances of the points 98 and 99 from the cam centre are equal in order to equalize the movement of the cam blocks. Return of the two rings and the brake shoes to initial positions is effected by means of the contractile spring 49.

In the construction illustrated in Figure 4, the lugs 4|, 42 of the guiding rings 3, 4, have slots 45, 46 in which flat sided pins 43, 44 can slide. These pins are mounted in the brake shoes 2|, 22.

Figure 5 shows the same slotted arrangement applied to a fourshoe brake. Each of the rings 3, 4 has four lugs each 41, 48, 49, 59. In the lugs are slots 55, 56, 51, in which the flat sided pins of the brake shoes can slide. The pins 61 are fixed in the brake carrier. The levers 66 are mounted on the pins 6'! and on the flat sided pins 52. The cam block 69 has extensions reaching to the middle of the brake shoe. At the ends of these extensions are holes in which the socket 6| is borne. In the socket is a thread for the screw 62. A worm wheel is connected with the screw 62 which is carried by a lug 63 on the rings 3, 4. The adjustment is effected by means of the worm 64. The return movement of the brake shoes to their normal positions is efiected by means of springs 68.

In the four-shoe brake shown in Figure 6, the lugs 69, 19, II, 12 which are part of the guiding rings 3, 4, have holes in which the pins 13, 14-, 15, 16, are rotatably mounted. In each of the brake shoes 81, 92 are two holes in which the pins 8|, 82, 83, 84 are carried. Corresponding ends of the levers I1, 18, 19, B9 are mounted on the pins I3, l4, 15, I6 and on the pins 8|, 82, 83, 84, the bolts being rotatable in the levers. The pin 99 which is fixed in the brake carrier passes through the slot 9| of the brake shoe 92. Corresponding ends of the lever 89 are mounted on the pins 82 and 99.

.The rings may be mounted on roller or needle bearings.

In Figure 7, a ring I93 turning on a stationary circular flange I92 fixed on the brake housing |9| has lugs I94 connected by pins I05 and links 36 to the pivot pins I01 carried by the brake shoes I08. The pivot pins [01 are connected by links I09 to the fixed pins Hi], the apertures in the links adjacent to the fixed pins being elongated as shown at Ill. The links I09 are pulled by springs H2. The'arrangement H3, I I' 4 applies power to the ring and the spacing between the part H4 and the lug Hi l can be adjusted by the arrangement H5, H6, H1. The shoes are connected to each other by guides H9 sliding in guideways I20.

In the constructional form of the invention shown in Figure 12, a single ring 183a is provided. This ring has two radially extending lugs l04a carrying pivot pins iflfia offset 180 from each other and disposed a short distance one on one side and one on the other side of a line conmeeting the middle points of two brake shoes 108a. The pins 1850. are connected by links lilta each to a pivot ll'lla carried by the brake shoe midway between its ends. These pivot pins are linked by links idea to pins llila carried by a fixed part. The apertures in these links engaged by the fixed pins I ifla are slightly elongated as at 11121. The two pairs of links form toggles, each pair being opened to about 90 or a little more. A short-rotary movement applied to the ring in one direction tends to collapse the toggles and force the shoes outwardly. The trailing end of each shoe is connected at 123a by a link i220. at l'lla to a radially outwardly projecting lug H211. on the ring I'BSa, whereby a parallel action of the shoes is ensured. A spring ie la pulls on a lug 125a for returning the ring to its normal position. Other springs 129a pull on the ends of the toggle links ifita adjacent to the fixed pins 1111a so that the elongated apertures i-l'la are drawn towards the trailing ends of the shoes. When the brake is applied, the braking force will tend to move the shoe in the direction of rotation of the brake drum, thereby increasing the pressure of the shoes through the leverage of the toggle links and of the links at the trailing ends of the shoes. The elongated apertures ll la permit any slight movement "of the shoes necessary for this purpose. A powerful servo action is thus exerted on both shoes.

*1 claim: a

l. A brake apparatus comprising a stationary wheel hub, brake shoes mounted concentrically about sa id hub, at least one rotatably mounted ringmeanssurrounding thewheel hub, combinati'on :l'c-ad multiplying and motion devices connectingthering means to th'e brake shoes whereby rotary movement applied to the ring means imparts outward motion to said shoes to apply the braking force, said devices'inciuding a pair of =circum'iereritially spaced cam blocks sliding incorresponding slots for connecting the ring to the shoes, a fixed guide pin for each shoe, and a link connecting said pin to said shoe, the point of connection of the link to the shoe lying outwardlyof and in advance o'f the fixed guide pin to produce 'a servo effect, and means for confining the shoes to limited radial and circumferential movement when in braking position.

2. *A brake apparatus comprising a stationary wheel hub, at least one 'arouate brake shoe, a pair-of rings rotatably'mounted about said 'hub, circumferentiall spaced cam -means between said ring's an'd shoe and operable upon reverse rotation of said rings for producing outward motion of the shoe with respect to said hub to thereby move said shoe to braking position, link means connecting said shoe to said hub, the point of connection of the link means to the shoe lying outwardly 'of the point of connection of the link means to the hub, said Flink means forming an angle with a radial line passing through said lastnamed point, and means for cooperating with said link means confining said shoe upon said hub to limited radial and circumferential movemen-t when (in braking position, whereby reverse rotation of said rings an equal amount will produce unequal radial movements of the shoe at the respective cam 'means.

3. A brake apparatus comprising a stationary wheel 'hub, at least one arcuate brake shoe, a pair of actuator rings rotatably mounted about said hub, cam means between one of said rings and said shoe for outwardly displacing one end of the shoe, secondcam means between the other of said rings :and said shoe for outwardly displacing the other =end of said shoe, means for oppositely rotating said rings whereby outward movement "of said shoe will be effected while moving to braking position, and means for producing unequal radial movement of the brake shoe at the first and second 'cam means respectively when said rings are oppositely rotated equal amounts.

4. a brake apparatus comprising a stationary wheel hub having at least one arcuate brake shoe, means for producing outward movement-of the shoe comprising a pair of relatively connection between one end of said shoe and one of said actuator members, a second pin and cam slot connection between the other end of said shoe and the other ot-said actuator members whereby relative movement of said actuator members will produce 'outwa-nd movement of the shoe, and means for producing unequal radial movement of the brake shoe at the first and second cam means respectively when said actuator members are moved equal amounts in=opposite directions.

-5. In -a brake apparatus according to claim 4 wherein said last-named means comprises a fixed pin on said hub intermediate said cam slot connections a second pin on'said shoe at a greater radial-distance from the center of said hub than said first pin and circumferentially spaced from the first pin, and a link connecting said pins whereby servo effect will be produced upon application of the brakes.

-6. The. brake apparatus according to claim 4 wherein :said-last-namedmeans comprises a fixed pinon said hub, anda link connecting said fixed pin with one'of the aforementioned'shoes whereby-aservoefiect isproduced upon application 0 the brakes.

EMIL-ZIPPER.

REFERENCES CITED .Ihe efollowingtreferences are of record in th file of dahis patent:

-=UNITED STATES PATENTS Number Name Date 1','739,78l Christensen Dec. 17', 1929 ;2;ll87553 Schiavon July 20, 1937, 2,184,050 Miles Dec. 19, 1939 2,3'76f889 Zipper May 19, 1945 

